<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    // function fn() {
    //   console.log(123)
    // }

    // fn()
    // fn()

    // function test() {
    //   fn()
    // }
    // test()

    function three() {
      console.log(333)
    }

    function one() {
      console.log(123)
      three()
    }

    function  two() {
      console.log(234)
      one()
    }

    two()

  </script>
</body>
</html>